Okay did extra iphone 4 to make sure no weird side effects, and it went so easy, they definitely have improved the process of the jailbreak. In the past their were so many stpes and putting it in DFU mode did not always work and screws the phone. Now onto a Itouch, a 3GS and 3G and Ipad 2 finally a iphone 5.
I have read a few people having issue with iphone 5 working after the jail break some people reported loss of serves and such.
The other thing is apple put out a warning as well that jailbreaking under IOS 6 could have some serious issue like lost battery life and I have send this problem before on the 3G and a little bit on the 3GS so jailbreak does have a downside.